Try unplugging power to the unit for 60 minutes, then plug back in and try again. This will reset the unit's microprocessor and hopefully clear the fault.
If your player is not reading any discs at all though, then try purchasing a can of compressed air (available at Staples, or Wal-Mart). Open the CD drawer, or remove the cover of the player (whichever you're most comfortable with), and spray the can approximately 10" from the lense itself to blow any dust off of it. If it still does'nt work, you can opt to clean the lense eye itself, by using isopropyl alcohol, and a link-free cloth to gently whipe the "eye". Then use a dry spot on the cloth to buff the eye clean. If the CD player is still not reading discs, then the eye or transport mechanism is faulty and would need to be replaced.
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